He is referring to Deferred Action for Childhood Arrivals, which President Barack Obama created by executive order in 2012. Trump's administration said Tuesday it is rescinding the program but is giving Congress six months to take action on it.

President Trump sent his reassuring tweet about so-called "Dreamers" at the urging of House Minority Leader Nancy Pelosi of California.

House Minority Leader Nancy Pelosi (D-CA) speaks at a news conference about President Donald Trump's decision to end the Deferred Action for Childhood Arrivals (DACA) program at the U.S. Capitol September 6, 2017 in Washington, D.C.
(Photo: Aaron P. Bernstein/Getty Images, 2015 Getty Images)

Pelosi revealed the news to fellow Democratic House members at a meeting Thursday morning. She says she spoke to Trump by phone and asked him to tweet to make clear that "Dreamers" wouldn't be subject to deportation during the six months Trump has given Congress to find a solution for them.

That's according to a Democratic aide who was not authorized to publicly discuss the private meeting and spoke on condition of anonymity.

At issue is Trump's plan to dismantle protections for younger immigrants who were brought illegally to the country as kids.

Trump is navigating politically tricky waters. Portions of his Republican voters wanting a hard line on illegal immigration. Yet others in his administration and a majority of Americans support protected status for children brought to the country illegally by their parents.